Diagnostic value of MRI signs in differentiating Ewing sarcoma from osteomyelitis.

Kasalak, Ömer; Overbosch, Jelle; Adams, Hugo J. A.; Dammann, Amelie; Dierckx, Rudi A. J. O.; Jutte, Paul C.; Kwee, Thomas C.; Adams, Hugo Ja; Dierckx, Rudi Ajo

<bold>Background: </bold>The value of magnetic resonance imaging (MRI) signs in differentiating Ewing sarcoma from osteomyelitis has not be thoroughly investigated.<bold>Purpose: </bold>To investigate the value of various MRI signs in differentiating Ewing sarcoma from osteomyelitis.<bold>Material and Methods: </bold>Forty-one patients who underwent MRI because of a bone lesion of unknown nature with a differential diagnosis that included both Ewing sarcoma and osteomyelitis were included. Two observers assessed several MRI signs, including the transition zone of the bone lesion, the presence of a soft-tissue mass, intramedullary and extramedullary fat globules, and the penumbra sign.<bold>Results: </bold>Diagnostic accuracies for discriminating Ewing sarcoma from osteomyelitis were 82.4% and 79.4% for the presence of a soft-tissue mass, and 64.7% and 58.8% for a sharp transition zone of the bone lesion, for readers 1 and 2 respectively. Inter-observer agreement with regard to the presence of a soft-tissue mass and the transition zone of the bone lesion were moderate (κ = 0.470) and fair (κ = 0.307), respectively. Areas under the receiver operating characteristic curve of the diameter of the soft-tissue mass (if present) were 0.829 and 0.833, for readers 1 and 2 respectively. Mean inter-observer difference in soft-tissue mass diameter measurement ± limits of agreement was 35.0 ± 75.0 mm. Diagnostic accuracies of all other MRI signs were all < 50%.<bold>Conclusion: </bold>Presence and size of a soft-tissue mass, and sharpness of the transition zone, are useful MRI signs to differentiate Ewing sarcoma from osteomyelitis, but inter-observer agreement is relatively low. Other MRI signs are of no value in this setting.

Acta Radiologica, 2019, Vol 60, Issue 2, p204

0284-1851

Academic Journal

10.1177/0284185118774953